Parallel universal access layer: A scalable I/O library for integrated tokamak modeling

The paper describes a parallel-I/O extension of the Universal Access Layer, a multi-language interface used for exchange of standardized data objects between Integrated Tokamak Modeling (ITM) codes. Although our evaluation focuses on Lustre, the general idea also applies to other parallel file systems. A snapshot of the current implementation is given, followed by an analysis of user and system requirements. The design derived from the serial version of the UAL is described, and emphasized features such as the ability to choose between serial and parallel I/O are explained. Performance tests comparing the implementation to other I/O methods are made to analyze the impact of the implementation. The outcome shows that the new implementation not only enables the I/O of datasets with several GB in size but also speeds up the write rate by a factor of 13 in the best case.